High flexibility of industrial robots can meet various special demands in modern environment-friendly casting production. By adopting robots in casting production, not only can operators be liberated from heavy and monotonous manual labor to save labor force, but also it is an important means to improve casting production efficiency and manufacturing precision and quality, and realize mechanization, automation and civilization of casting production. At present, adopting advanced and applicable new casting technologies, improving casting equipment automation and particularly applying mobile robot technologies are key measures taken by casting enterprises to implement environment-friendly casting production and realize sustainable development. Since casting is performed in severe environments of high temperature, high dust, vibration, oil containment, noise and electromagnetic interference, and the weight of castings is great, common industrial robots cannot meet production demands. There are numerous key technologies which need to be urgently studied and broken through for casting robots in order to adapt to such working environments and operate normally. Casting robots not only can be used for handling and conveying castings in pressure casting and precision casting production, but also can be used in processes such as modeling, core making, core setting, pouring, cleaning and inspection of sand mold casting. Especially in production of medium-size and large-size castings, sizes and weights of sand cores and castings are comparatively great, the difficulty in executing core picking, core assembling, core setting and handling operations is great and the requirements are high. High-flexibility and high-load casting robots which can meet demands of operations such as core picking, core assembling, core setting and handling in casting production are urgently needed. When casting robots execute operation tasks such as core picking, core assembling, core setting and handling, in addition to robot bodies, robot grippers used as end executors are important key equipment.
At present, robot grippers used for gripping castings and mold cores can only continuously grip castings and mold cores of a single specification or with regular shapes, manual adjustment or gripper replacement is needed and automatic adjustment cannot be realized when specifications or shapes of castings or mold cores change, and since operators need to enter robot working areas to make adjustment, potential safety hazards of operators are increased and the working efficiency of robots are reduced. At the same time, continuous working of one robot to different specifications of workpieces cannot be realized, i.e., flexible work of one machine for multiple use cannot be realized.
Aiming at the problems existing in casting gripping, existing literal documents provide some solutions. Chinese patent application No. 201210051811.5 discloses a robot hand comprising a palm, a plurality of fingers, a motor reducer, wires, ropes and the like, gripping of workpieces is realized by controlling the palm and fingers, but the gripper can only realize angle adjustment, the universality is poor, the working space is small and the gripping of large-size castings and castings with complex shapes cannot be realized. Chinese patent application No. 201710029023.9 discloses a multipurpose robot arm gripper structure comprising a base, a gripper arm, a cylinder, a turnover supporting plate, a linking plate and a controller, the structure is simple, the length of the gripper arm cannot be adjusted according to the size of castings, the stability during casting gripping is poor, the working space is relatively small and the gripping of castings with complex structures cannot be satisfied. Chinese patent application No. 201510570943.2 discloses a multi-finger spindle gripping robot gripper comprising a connecting plate, a plurality of grippers and a plurality of cylinders, gripping of workpieces with simple shapes and structures is realized, the adaptability is poor, the length of the gripper is fixed, the stability is poor and the operation requirements of complex castings cannot be met. Chinese patent application No. 201410281605.2 discloses a multifunctional robot gripper consisting of a motor driving part, a vacuum cup and a mechanical gripper part, the vacuum cup is not applicable to large-size castings with complex surfaces, the working space of the mechanical gripper is small and the working efficiency is low. Chinese patent application No. 201110297466.9 provides a robot gripper device, a gripping part is driven to slide through a sliding mechanism to adjust a gripping position, the positioning accuracy is high, the gripper itself cannot be adjusted, consequently an optimum gripping position cannot be selected in a gripping process and operation requirements of specially-shaped castings cannot be realized. Chinese patent application No. 201010605168.7 discloses a robot gripper comprising a cylinder body, a bidirectional cylinder, a locating pin and a gripping nipper, and this gripper has the following disadvantages during operation: 1) the flexibility is low and the adaptability is limited; 2) the gripping stability is poor; and 3) the operation requirements of complex castings with specially-shaped sections cannot be met. Chinese patent application No. 201410689752.3 discloses a robot gripper device comprising a mechanical gripper, a sliding block, a lifting member, a mounting plate and a pull-up member, the gripping and lifting of workpieces are realized, but the working piece of the gripper is very greatly limited, the flexibility of the gripper is low, the working efficiency is low and the task of gripping castings with complex structures cannot be realized. Chinese patent application No. 201510792769.6 provides an adaptive robot dual-gripper device comprising a mounting flange, a gripper support, a gripper assembly and a gripper adjusting device, dual grippers can realize gripping of workpieces, but the working space is small, it is difficult to realize gripping of large-size castings, the flexibility of dual grippers is low, the stability is poor and the operation requirements of castings with complex surfaces cannot be realized.
With the continuous development and improvement of casting technologies, the demands for medium-size and large-size casting production and casting gripping automation become increasingly high. Most grippers in the existing technical solutions cannot meet the demands of operations for gripping heavy-weight and large-volume castings with complex surface structures.